You can never eradicate a disease - causing fungus, but if you remove the conditions it finds favorable, you will often stop disease development. The fungus will always be in the soil: but it will only be a problem if the weather (or irrigation) conditions and grass conditions are right for it. So the key to disease control often lies in trying to provide conditions favorable for the grass but not the fungus. For example don’t over - water and don’t over - fertilize.